The present invention relates generally to motor vehicle speed sensors.
Transmission-mounted vehicle speed sensors have been provided to sense the speed of a vehicle. Typical transmission speed sensors have a one-piece external housing that is molded around an internal sensing structure. The high temperatures associated with the molding process can have detrimental effects on the sensing structure and affect long term performance. Moreover, many vehicles have sensors of different lengths. To accommodate the different lengths, the internal parts must be different. As such, there is a lack of standardization of parts which increases manufacturing costs.
As such, the present invention recognizes the need for a speed sensor that eliminates the exposure of internal components to high molding temperatures during manufacture. There is also a need for a speed sensor that uses standard-sized parts regardless of its length.
A vehicle speed sensor includes a sensor housing that has an open end, a sensing structure within the sensor housing, and a connector housing that is installed in the open end of the sensor housing. As envisioned in the particularly preferred embodiment set forth in detail below, the connector housing is formed with at least one engagement groove and the sensor housing is formed with at least one engagement rib coupled to the groove. Prior to coupling, to establish a predetermined length of the sensor, the connector housing (134) is slidable relative to the sensor housing. Once the length is established, the rib is heat staked to the groove.
Preferably, the connector housing also forms at least one o-ring groove and the vehicle speed sensor has an o-ring disposed within the o-ring groove to establish a seal between the sensor housing and the connector housing. Additionally, the sensing structure has a spool with a pole piece holder that supports a pole piece and a coil that is disposed around the pole piece. Moreover, the vehicle speed sensor has a connector supported by the connector housing, and the connector is electrically connected to the coil.
In a preferred embodiment, the connector housing forms a socket around the connector and the socket is sized to engage a complementarily-shaped and sized electrical connector. Also, the connector housing defines a first axis and the sensor housing defines a second axis that is orthogonal to the first axis. In order to be properly positioned in a transmission housing, the sensor housing has an outer wall that further has an abutment flange that can abut a transmission housing.
As described further below, the vehicle speed sensor can be inserted into a vehicle transmission fluid so that the pole piece contacts the transmission fluid. The sensing structure further has at least one magnet magnetically coupled to the pole piece, and the coil surrounds at least a portion of the pole piece. The spool holds the magnet and the pole piece and is disposed between the coil and the pole piece.
In another aspect of the present invention, a vehicle speed sensor has a sensor housing with an open end, and the sensor housing forms at least one engagement rib. A sensing structure is disposed within the sensor housing. Additionally, a connector housing is coupled to the open end of the sensor housing. At least one engagement groove is formed in the connector housing. As discussed below, the groove receives the engagement rib and the two are heat-staked together to bond the sensor housing to the connector housing.